Federal authorities say they’ve taken down one of the nation’s biggest “cramming” operations, those so-called businesses that stuff unwanted charges to your cell phone bill in increments tiny enough to go unnoticed.

The Federal Trade Commission filed a lawsuit Monday against several companies based in Los Angeles and Boston that managed to stick millions of dollars worth of bogus charges to unsuspecting consumers’ cell phone bills — most of which were paid without even a blink, the government says.

“The practice, known as mobile cramming, relies on the fact that consumers often don’t closely examine their monthly statements, or many assume that charges are legitimate,” the FTC said in a release announcing the court action.

Charges are as small as $9.99 and, because so many bills are prepaid or automatically covered by credit card or bank withdrawal, consumers simply don’t notice the payments.

Too, the scammers would often cram the charges — which happens simply by using a coding system that cell phone carriers see as legitimate and post it on an account — with indecipherable labels that appear to be legitimate taxes or fees, such as “77050IQ12CALL8663611606” and “25184USBFIQMIG.”

As part of its case in U.S. District Court in central California, the FTC was granted a temporary restraining order against the defendants and all assets were frozen.

The FTC estimates consumers unknowingly paid millions of dollars for the phony charges. Some complained to their cell carrier but could recoup only about 40 percent of what they paid.

The purported services included, among other gems: “Hollywood Stars Live! Alerts” and “MyLuvCrush.”

Moral of the story: keep track of your phone bills and review it each and every month, even if it’s on auto-pay.

Emilie Rusch covers retail and commercial real estate for The Post. A Wisconsin native and Mizzou graduate, she moved to Colorado in 2012. Before that, she worked at a small daily newspaper in South Dakota. It's the one with Mount Rushmore.